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custom kernel install - query
by Sengottuvelan S Dec. 22, 2010

Dec. 22, 2010

Hi all I am trying to install new custom kernel in my ubundu. I am able to see "vmlinuz-2.6.x.x-custom-velan" and System.map-2.6.x.x-custom-velan in my /boot after #make-kpkg --initrd --append-to-version=-custom_velan kernel_image kernel_headers i don;t see initrd for this new custom kernel in /boot and also no entry is created in /boot/grub/grub.cfg. I also don't see any new file "menu.lst" in /boot/grub directory. I am using generic kernel as below. root@ubuntu:/usr/src/linux# uname -a Linux ubuntu 2.6.32-24-generic #39-Ubuntu SMP Wed Jul 28 05:14:15 UTC 2010 x86_64 GNU/Linux Can you throw some light on this. -- Regards, S. Sengottuvelan.

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Need help EHCI host driver on Linux 2.6.29
by CL Lee Dec. 22, 2010

Dec. 22, 2010

Dear Experts, I am developing a EHCI host driver for Linux kernel 2.6.29 on a proprietary SoC. But for weeks now, I am troubleshooting a time out error from khubd. I believe it's related to the client device not being able to update the qtd struct which has been set at some Dma addresses, say 0x87xxxxxx. Is this possible? The main issue is the register address for chip lies in 0x5a800000 range, so is the on-chip memory. If I set the qtd structs to on chip memory(internal sram), kernel paging error will occur. So I am at a loss of what I can. Please kindly advise. Best regards, CL

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Re: Recursive function in Kernel space
by Mulyadi Santosa Dec. 22, 2010

Dec. 22, 2010

On Wed, Dec 22, 2010 at 13:02, Darshan Ghumare <darshan.ghumare(a)gmail.com> wrote: > > Sir, > I have following question, > Why recursive function is not recommended in Kernel-Space? because kernel stack is limited...about 8K...or 4K if you choose to have such amount... -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com

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Accessing PCI Memory Mapped Registers in Linux Kernel
by YOUNGWHAN SONG Dec. 22, 2010

Dec. 22, 2010

Hi, A few days ago, I posted about accessing PCI memory mapped registers. (FYI, the platform I use is 32bit architecture and Linux kernel compiled in 32 bit intel based architecture.) Now, I found that there is a problem to access 16b aligned registers. For example, ------------- struct foo { unsigned int TEST1; unsigned short int a1[256]; } void * regsva; struct foo *test_foo; if ((regsva = ioremap_nocache(dev->base_addr, (16 * 1024))) == NULL) { printk("ioremap() failed\n"); goto fail; } test_foo = (struct foo*)regsva; printk(KERN_DBG "value TEST1: 0x%lx\n", readl(test_foo->TEST1)); printk(KERN_DBG "value 0: 0x%x\n", readw(&test_foo->a1[0]); printk(KERN_DBG "value 1: 0x%x\n", readw(&test_foo->a1[1]); ------------- The above code in PC (intel based 32bit architecture) with the same h/w module shows that value TEST1: 0x8080 value 0: 0x9090 value 1: 0xa0a0 So, that's valid value. (I have datasheet to check if the value is correct or not.) But, when the code is run on our platform (32bit) with the same h/w module, it shows that value TEST1: 0x8080 value 0: 0xFFFF value 1: 0xFFFF Now, if I change the printk as printk(KERN_DBG "value 0: 0x%x\n", readl(&test_foo->a1[0]); printk(KERN_DBG "value 1: 0x%x\n", readl(&test_foo->a1[1]); Then, even PC shows 0xFFFF like this: value 0: 0xFFFFFFFF value 1: 0xFFFFFFFF So, if the read bit is not aligned correctly, it looks it cannot read correctly. OK, then, How can our platform (32 bit) read correctly 16b aligned PCI memory mapped register? (As long as the register is 32 bit, there is no problem.) At least, I would like to understand why the 16 bit registers and 32 bit registers are responding differently. Thanks, Daniel

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Problem with booting newly compiled kernel
by Prasad Joshi Dec. 22, 2010

Dec. 22, 2010

Hello, I seem to be always getting stuck in the new kernel booting. The problem is with mounting of the root file system. I don't have the log of the messages but, I guess, these were the messages reported VFS: Cannot open root device ............ Please append a correct "root=" boot option; here are the available partitions: Device: sda driver: sd ....... list of all partitions on sda, including correct size, offset of each parition ....... Device sdb driver: sr Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0) Backtrace: It reported the correct list of sda partitions, including the driver name as sd. I have a SATA disk and the root partition has ext4 file system. The ext2/3/4 code is compiled as a part of the kernel. $ df -kh / Filesystem Size Used Avail Use% Mounted on /dev/sda1 459G 13G 423G 3% / As far as I can understand, as it is showing the correct list of partitions, the problem is not with the block device driver. But I am not sure, why it is failing to mount the file system when ext4 is also part of the kernel. grub.cfg file. menuentry 'Ubuntu, with Linux 2.6.37-rc6+' --class ubuntu --class gnu-linux --class gnu --class os { recordfail insmod part_msdos insmod ext2 set root='(hd0,msdos5)' search --no-floppy --fs-uuid --set ab9dfe8f-8e58-43ca-b16f-a42e0f02da72 linux /vmlinuz-2.6.37-rc6+ root=UUID=01432597-18e7-4609-9f85-3fad1d762ddc ro iommu=1 initrd /initrd.img-2.6.37-rc6+ } menuentry 'Ubuntu, with Linux 2.6.35-22-generic' --class ubuntu --class gnu-linux --class gnu --class os { recordfail insmod part_msdos insmod ext2 set root='(hd0,msdos5)' search --no-floppy --fs-uuid --set ab9dfe8f-8e58-43ca-b16f-a42e0f02da72 linux /vmlinuz-2.6.35-22-generic root=UUID=01432597-18e7-4609-9f85-3fad1d762ddc ro iommu=1 quiet splash initrd /initrd.img-2.6.35-22-generic } The kernel 2.6.35-22-generic boots correctly. Thanks and Regards, Prasad

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Re: A query on page cache and writepage
by Shreyansh Jain Dec. 21, 2010

Dec. 21, 2010

Hi Prasad, (My comment inline) On Sat, Dec 18, 2010 at 5:24 PM, Rajat Sharma <fs.rajat(a)gmail.com> wrote: > I am not sure if memory what for your filesystem needs mapping, may be to > support binary execution. Do you really need to support Writable or Shared > memory mappings? If you are good with Read-only mappings or Private memory > mapping (which does not modify data in page cache but modify a temporary > COWed copy), the solution is simple - do not implement writepage method at > all, there won't be any dirty data in page cache at any point of time, so no > need to flush page cache, however you need to discard page cache range when > you modify the file through f_op->write(), otherwise memory mapped files > will read stale data. > > Rajat > > On Sat, Dec 18, 2010 at 6:51 AM, Prasad Joshi <prasadjoshi124(a)gmail.com> > wrote: >> >> Hello All, >> >> I am working on a file system, that uses page cache only if a file is >> memory mapped. This is how the code is designed >> >> write() >> { >> write the data onto the disk >> >> if (file not memory mapped) >> return; >> >> /* file is memory mapped */ >> while (till all data is not syced with page cache) { >> if (data at current file offset held in page) { >> update the page >> } >> } >> } >> >> The code that updates a page is something like this >> page = find_lock_page(mapping, index); >> if (likely(!page)) { >> /* page not cached */ >> continue; >> } >> >> if (mapping_writably_mapped(mapping)) >> flush_dcache_page(page); >> >> pagefault_disable(); >> >> /* copy the data */ >> BUG_ON(!in_atomic()); >> page_buf = kmap_atomic(page, KM_USER0); >> if (__copy_from_user_inatomic(page_buf+offset, user_buf, size)) { >> kunmap(page); >> unlock_page(page); >> err = -EFAULT; >> goto out_error; >> } >> kunmap_atomic(page_buf, KM_USER0); >> pagefault_enable(); >> >> flush_dcache_page(page); >> mark_page_accessed(page); >> >> SetPageUptodate(page); >> ClearPageError(page); >> unlock_page(page); >> page_cache_release(page); >> >> If a fops->write() is called the data in page cache is already on to >> the disk. I don't want a page update from this function to trigger >> writepage() function. >> >> The writepage() function should only be called if an user updates a >> memory mapped page. >> >> Would calling page_clear_dirty() from the write() code be sufficient? Are you sure that once you have cleared the dirty bit no other process mapping this file is performing any modifications? If yes, probably that should suffice. >> >> I need to call flush_dcache_page() as a page should be coherent with >> other mappings. Does calling flush_dcache_page() result in call to >> writepage()? I very faintly remember that flush_dcache_page would invoke the mmap operations which in turn would converge back into a filesystem specific writepage call. Hence, I would expect writepage to be called for dcache flush operation. Probably this might be helpful: http://lxr.linux.no/#linux+v2.6.36/Documentation/cachetlb.txt#L279 Also, had I been in your shoes, I would have actually put a printk like thing in my writepage operation to confirm if indeed my function was not getting called from any kernel specific threads (like pdflush etc). [Please take my suggestions with a pinch of salt as I have been out of touch with this topic since ages - and in case you find them incorrect, I would be very thankful in case you can correct me too] -- Shreyansh

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Re: writing boot loader
by vamidhar s Dec. 21, 2010

Dec. 21, 2010

processor -bcm53003 its mips 32 . i am planning to port linux 2.6.27. i got some reference code to builld cfe bootloader,but i dont know where to start in that code. bootloader has to perform these low level initialization Reset and ROM trap handler vectors • CPU and FPU initialization • L1 and L2 Cache initialization • Multiprocessor initialization • Memory controller initialization • PCI and LDT bus configuration • Environment variables • Console device initialization • Bootstrap device initialization On Fri, Dec 17, 2010 at 7:57 PM, Chaitannya Mahatme <chaitannya(a)gmail.com>wrote: > On Friday 17 December 2010 03:05 PM, Anuz Pratap Singh Tomar wrote: > > > > On Fri, Dec 17, 2010 at 8:46 AM, Mahatme <chaitannya(a)gmail.com> wrote: > >> Hi Vamidhar, >> >> >> You need to provide more information regarding your development. What >> bootloader you want to install / create depends on many factors >> >> 1. What is your target application. >> 2. Chip architecture : does it have MMU (most significant parameter) >> 3. Is there a bootloader existing for the architecture (u-boot / Grub >> / Lilo ) have ready made ports for lot of architectures. You would have to >> see if they already have done the development. >> 4. What OS you are planning to port.. or there is no OS to be >> installed. E.g. some bootloaders like u-boot are optimized for Linux >> kernel. >> >> Please answer to those question so that you would get more relevant >> answer. >> >> Chaitannya, > > its utterly rude to top post. Please don't do that.(read community > guidelines) > > its most likely Linux(if not, probably this in not the list for it), and > there were couple of mails where he did discuss about arch and detail. > > > > > Got your point... It's just that I am following this convention since past > 10 years (No one told me it was rude). > Also about the Vamidhar post I did not find any old reference. > > > -- > Cheers !!! > Chaitannya > > follow me on twitter http://twitter.com/chaitannya > > I believe there's a hero in all of us > who keeps us honest, gives us strength, makes us noble, and finally allows > us to die with pride, > even though sometimes we have to be steady, and give up the thing we want > the most... even our dreams. > - Spider Man 2 > -- To unsubscribe from this list: send an email with "unsubscribe > kernelnewbies" to ecartis(a)nl.linux.org Please read the FAQ at > http://kernelnewbies.org/FAQ

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Low on disk space after compiling new kernel.
by Rishi Agrawal Dec. 21, 2010

Dec. 21, 2010

Hi All, I installed the kernel 2.6.36 into my Fedora 12 system. I am now low on disk space. [root@rishi-desktop kernels]# du -sh linux-2.6.36/ 4.4G linux-2.6.36/ It shows that the new compiled kernel is taking around 4.4GB. The /lib/modules/2.6.36 is taking around 780M on my disk. I wanted to free some of the space occupied by the compiled code. I understand that the /lib/modules/2.6.36 directory can't be deleted as it contains the compiled modules. I wanted to delete the files in /usr/src/kernel/2.6.36, without effecting my newly installed kernel. -> Can I delete them? -> What is the best way to delete them, I want to keep the source files? -> Should I run make clean to remove the compiled code? -> Any other way? -- Regards, Rishi Agrawal

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Suggestion for the LISTDOMAIN
by Michelle Konzack Dec. 20, 2010

Dec. 20, 2010

Hello * and owners of <kernelnewbies.org>, since I am ISP I am runing into troubles with spam coming from listservers or faked Froms: I suggest you to CHANGE the LISTDOMAIN from kernelnewbies.org to lists.kernelnewbies.org which makes spamfiltering much easier. Thanks, Greetings and nice Day/Evening Michelle Konzack -- ##################### Debian GNU/Linux Consultant ###################### Development of Intranet and Embedded Systems with Debian GNU/Linux itsystems@tdnet France EURL itsystems@tdnet UG (limited liability) Owner Michelle Konzack Owner Michelle Konzack Apt. 917 (homeoffice) 50, rue de Soultz Kinzigstraße 17 67100 Strasbourg/France 77694 Kehl/Germany Tel: +33-6-61925193 mobil Tel: +49-177-9351947 mobil Tel: +33-9-52705884 fix <http://www.itsystems.tamay-dogan.net/> <http://www.flexray4linux.org/> <http://www.debian.tamay-dogan.net/> <http://www.can4linux.org/> Jabber linux4michelle(a)jabber.ccc.de Linux-User #280138 with the Linux Counter, http://counter.li.org/

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Suggestion for the LISTDOMAIN
by Michelle Konzack Dec. 20, 2010

Dec. 20, 2010

Hello * and owners of <kernelnewbies.org>, since I am ISP I am runing into troubles with spam coming from listservers or faked Froms: I suggest you to CHANGE the LISTDOMAIN from kernelnewbies.org to lists.kernelnewbies.org which makes spamfiltering much easier. Thanks, Greetings and nice Day/Evening Michelle Konzack -- ##################### Debian GNU/Linux Consultant ###################### Development of Intranet and Embedded Systems with Debian GNU/Linux itsystems@tdnet France EURL itsystems@tdnet UG (limited liability) Owner Michelle Konzack Owner Michelle Konzack Apt. 917 (homeoffice) 50, rue de Soultz Kinzigstraße 17 67100 Strasbourg/France 77694 Kehl/Germany Tel: +33-6-61925193 mobil Tel: +49-177-9351947 mobil Tel: +33-9-52705884 fix <http://www.itsystems.tamay-dogan.net/> <http://www.flexray4linux.org/> <http://www.debian.tamay-dogan.net/> <http://www.can4linux.org/> Jabber linux4michelle(a)jabber.ccc.de Linux-User #280138 with the Linux Counter, http://counter.li.org/

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